Forschungsdatenbank PMU-SQQUID

PMU-Autor/inn/en

Abstract

AIM
Description of the effects of hypotonic cell swelling and ethanol on maxi Ca2+-activated K+ channel (BK channel) activity and Cl- channel activity in GH4/C1 pituitary tumour cells.
Whole cell-, cell attached- and outside-out patch clamp measurements, fluorescence (fluo-3) measurements of intracellular Ca2+ concentration, cell size video monitoring.
GH4/C1 pituitary tumour cells respond to both hypotonicity and ethanol with cell swelling which is followed by a regulatory volume decrease (RVD). Tetraethylammonium and 4,4"-diisothiocyanatostilbene-2,2"-disulphonic acid (DIDS) induced cell swelling per se and inhibited hypotonicity induced RVD. Ethanol-induced swelling is paralleled by an increase in the intracellular Ca2+ concentration and augmented by DIDS. BK channel activation by hypotonicity and ethanol is demonstrated in patch clamp experiments both in intact cells (cell attached configuration) and a subset of excised membrane patches (outside-out configuration). Cell swelling and addition of ionomycin under isotonic conditions leads to the activation of outwardly rectifying Cl- currents with time dependent activation at positive potentials.
In GH4/C1 cells both hypotonicity and ethanol lead to cell swelling, RVD and to activation of BK channels. The hypotonicity-induced BK channel activation can also be observed in cell free outside-out patches. Hypotonicity, but not ethanol leads to the activation of Cl- channels with features of Ca2+-activated Cl- currents.

Useful keywords (using NLM MeSH Indexing)

3T3 Cells

4,4"-Diisothiocyanostilbene-2,2"-Disulfonic Acid/pharmacology

Animals

Calcium/metabolism

Cell Line, Tumor

Cell Membrane/metabolism

Cell Size

Central Nervous System Depressants/pharmacology*

Chloride Channels/metabolism*

Ethanol/pharmacology*

Humans

Hypotonic Solutions/pharmacology*

Mice

Microscopy, Video

Patch-Clamp Techniques

Pituitary Neoplasms/metabolism*

Potassium Channel Blockers/pharmacology

Potassium Channels/metabolism

Tetraethylammonium/pharmacology

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